When extracorporeal lithotripsy was developed and used for the treatment of kidney stones, it was observed that the pressure shock waves may have an anti-bacterial effect. Some of the kidney stones incorporate bacteria in them (due to their bacterial etiology) and after stone fragmentation, a higher rate of infection was expected, at least until the stone fragments were passed naturally. That was not the case when lithotripsy pressure shock waves were used, which pointed out toward bactericidal effect of the pressure shock waves. The same bactericidal phenomenon was observed during wound treatment using pressure shock waves.
The above-mentioned observations triggered extensive pre-clinical studies using laboratory cell cultures or animals. These studies showed that pressure shock waves can destroy, reduce proliferation of most common Gram positive and Gram negative, aerobic and anaerobic bacteria or break bacterial biofilms. The targeted bacteria included Staphylococcus aureus, Methycillin-resistant Staphylococcus aureus (MRSA), Streptococcus mutans, Actinomyces naeslundii, Porphyromonas gingivalis and Fusobacterium nucleateum. 
The killing of bacteria is suggested to result from a combination of the following mechanisms:                strong mechanical forces generated by pressure shock waves that can disrupt biofilms;        cavitation microjets generated by collapsing cavitation bubbles can kill bacteria or disrupt biofilms;        localized thermal effects produced by collapsing cavitation bubbles can also kill bacteria; and        shock waves generated free radicals can have a destructive effect on bacteria or biofilms.        
A similar effect as the one observed for bacteria was also shown in viruses. Based on preclinical studies, it is suggested that pressure shock waves can disrupt the outer membrane of the viruses and the bacteria that hosts the virus and thus killing them.
Another important observation from prior studies is that the membrane of the viruses and bacteria seems to be less flexible when compared with normal tissue cells or fluidic cells (as red blood cells), which makes bacteria and viruses more prone for destruction by the combined mechanisms generated by the pressure shock waves (compressive pressures combined with high velocity cavitation microjets).
Based on the above observations, a need exists to adapt the use of pressure shock waves in order to eliminate bacteria from fluids or from solid networks that might be filled with fluids. Further, a need exists to similarly use shock waves to disrupt viruses (immunodeficiency virus—HIV, hepatitis viruses, papilloma virus, herpes simplex virus, etc.) and to kill different micro-organisms such as giardia lamblia, legionella, cryptosporidium, and the like.